ErrorType#name must be CamelCase (#13)

Author: uschi2000

errors/src/main/java/com/palantir/remoting/api/errors/ErrorType.java

@@ -16,6 +16,7 @@
 
 package com.palantir.remoting.api.errors;
 
+import java.util.regex.Pattern;
 import org.immutables.value.Value;
 
 /**
@@ -26,6 +27,8 @@
 @ImmutablesStyle
 public abstract class ErrorType {
 
+    private static final Pattern UPPER_CAMEL_CASE = Pattern.compile("([A-Z][a-z]+)+");
+
     public enum Code {
         UNKNOWN(500),
         PERMISSION_DENIED(403),
@@ -41,11 +44,11 @@ public enum Code {
         }
     }
 
-    public static final ErrorType UNKNOWN = create(Code.UNKNOWN);
-    public static final ErrorType PERMISSION_DENIED = create(Code.PERMISSION_DENIED);
-    public static final ErrorType INVALID_ARGUMENT = create(Code.INVALID_ARGUMENT);
-    public static final ErrorType FAILED_PRECONDITION = create(Code.FAILED_PRECONDITION);
-    public static final ErrorType INTERNAL = create(Code.INTERNAL);
+    public static final ErrorType UNKNOWN = createInternal(Code.UNKNOWN, "Unknown");
+    public static final ErrorType PERMISSION_DENIED = createInternal(Code.PERMISSION_DENIED, "PermissionDenied");
+    public static final ErrorType INVALID_ARGUMENT = createInternal(Code.INVALID_ARGUMENT, "InvalidArgument");
+    public static final ErrorType FAILED_PRECONDITION = createInternal(Code.FAILED_PRECONDITION, "FailedPrecondition");
+    public static final ErrorType INTERNAL = createInternal(Code.INTERNAL, "Internal");
 
     /** The {@link Code} of this error. */
     public abstract Code code();
@@ -59,6 +62,13 @@ public enum Code {
     /** The HTTP error code used to convey this error to HTTP clients. */
     public abstract int httpErrorCode();
 
+    @Value.Check
+    final void check() {
+        if (!UPPER_CAMEL_CASE.matcher(name()).matches()) {
+            throw new IllegalArgumentException("ErrorType names must be UpperCamelCase: " + name());
+        }
+    }
+
     /**
      * Creates a new error type with the given name and HTTP error code, and error type{@link Code#CUSTOM}.
      * Allowed error codes are {@code 400 BAD REQUEST} and {@code 500 INTERNAL SERVER ERROR}.
@@ -82,17 +92,13 @@ public static ErrorType of(Code code, String name) {
         if (code == Code.CUSTOM) {
             throw new IllegalArgumentException("Use the custom() method to construct ErrorTypes with code CUSTOM");
         }
-        return ImmutableErrorType.builder()
-                .code(code)
-                .name(name)
-                .httpErrorCode(code.httpErrorCode)
-                .build();
+        return createInternal(code, name);
     }
 
-    private static ErrorType create(Code code) {
+    private static ErrorType createInternal(Code code, String name) {
         return ImmutableErrorType.builder()
                 .code(code)
-                .name(code.name())
+                .name(name)
                 .httpErrorCode(code.httpErrorCode)
                 .build();
     }

errors/src/test/java/com/palantir/remoting/api/errors/ErrorTypeTest.java

@@ -23,6 +23,23 @@
 
 public final class ErrorTypeTest {
 
+    @Test
+    public void testNameMustBeCamelCase() throws Exception {
+        assertThatThrownBy(() -> ErrorType.of(ErrorType.Code.FAILED_PRECONDITION, "foo"))
+                .isInstanceOf(IllegalArgumentException.class)
+                .hasMessageStartingWith("ErrorType names must be UpperCamelCase: foo");
+
+        assertThatThrownBy(() -> ErrorType.custom("foo", 400))
+                .isInstanceOf(IllegalArgumentException.class)
+                .hasMessageStartingWith("ErrorType names must be UpperCamelCase: foo");
+        assertThatThrownBy(() -> ErrorType.custom("fooBar", 400))
+                .isInstanceOf(IllegalArgumentException.class)
+                .hasMessageStartingWith("ErrorType names must be UpperCamelCase: fooBar");
+        assertThatThrownBy(() -> ErrorType.custom("", 400))
+                .isInstanceOf(IllegalArgumentException.class)
+                .hasMessageStartingWith("ErrorType names must be UpperCamelCase: ");
+    }
+
     @Test
     public void testDefaultErrorTypeHttpErrorCodes() throws Exception {
         assertThat(ErrorType.UNKNOWN.httpErrorCode()).isEqualTo(500);
@@ -34,29 +51,29 @@ public void testDefaultErrorTypeHttpErrorCodes() throws Exception {
 
     @Test
     public void testCustomErrors() throws Exception {
-        ErrorType custom400 = ErrorType.custom("myDesc", 400);
+        ErrorType custom400 = ErrorType.custom("MyDesc", 400);
         assertThat(custom400.code()).isEqualTo(ErrorType.Code.CUSTOM);
         assertThat(custom400.httpErrorCode()).isEqualTo(400);
-        assertThat(custom400.name()).isEqualTo("myDesc");
+        assertThat(custom400.name()).isEqualTo("MyDesc");
 
-        ErrorType custom500 = ErrorType.custom("myDesc", 500);
+        ErrorType custom500 = ErrorType.custom("MyDesc", 500);
         assertThat(custom500.code()).isEqualTo(ErrorType.Code.CUSTOM);
         assertThat(custom500.httpErrorCode()).isEqualTo(500);
-        assertThat(custom500.name()).isEqualTo("myDesc");
+        assertThat(custom500.name()).isEqualTo("MyDesc");
 
-        assertThatThrownBy(() -> ErrorType.custom("myDesc", 403))
+        assertThatThrownBy(() -> ErrorType.custom("MyDesc", 403))
                 .isInstanceOf(IllegalArgumentException.class)
                 .hasMessage("CUSTOM ErrorTypes must have HTTP error code 400 or 500");
     }
 
     @Test
     public void testCanCreateNewErrorTypes() throws Exception {
-        ErrorType error = ErrorType.of(ErrorType.Code.FAILED_PRECONDITION, "myDesc");
+        ErrorType error = ErrorType.of(ErrorType.Code.FAILED_PRECONDITION, "MyDesc");
         assertThat(error.code()).isEqualTo(ErrorType.Code.FAILED_PRECONDITION);
         assertThat(error.httpErrorCode()).isEqualTo(400);
-        assertThat(error.name()).isEqualTo("myDesc");
+        assertThat(error.name()).isEqualTo("MyDesc");
 
-        assertThatThrownBy(() -> ErrorType.of(ErrorType.Code.CUSTOM, "myDesc"))
+        assertThatThrownBy(() -> ErrorType.of(ErrorType.Code.CUSTOM, "MyDesc"))
                 .isInstanceOf(IllegalArgumentException.class)
                 .hasMessage("Use the custom() method to construct ErrorTypes with code CUSTOM");
     }

errors/src/test/java/com/palantir/remoting/api/errors/ServiceExceptionTest.java

@@ -26,8 +26,8 @@
 
 public final class ServiceExceptionTest {
 
-    private static final ErrorType ERROR = ErrorType.custom("myDesc", 400);
-    private static final String EXPECTED_ERROR_MSG = "ServiceException: CUSTOM (myDesc)";
+    private static final ErrorType ERROR = ErrorType.custom("MyDesc", 400);
+    private static final String EXPECTED_ERROR_MSG = "ServiceException: CUSTOM (MyDesc)";
 
     @Test
     public void testExceptionMessagesContainsSafeArgsOnly() {